Why influenza is more dangerous during pregnancy

New study finds that pregnant women and their babies might be at an even greater risk for the flu virus.

Only about half of pregnant women currently get vaccinated for the flu. (Photo: Image Point Fr/Shutterstock)

Should pregnant women get the flu vaccine? Health experts say the answer is a resounding yes. Not only are moms-to-be more vulnerable to getting influenza, they also get much sicker than their non-pregnant peers, and that could be bad news for both mom and baby.

According to new research from Stanford University and Lucile Packard Children’s Hospital, pregnant women have a heightened immune response when they are exposed to the flu. For the study, which was published in the Proceedings of the National Academy of Sciences, researchers compared the immune cells of 21 nonpregnant women to those of 29 pregnant women. They found that the moms-to-be were not only more responsive to influenza viruses immunologically, but also had a higher level of immune response one week after getting the flu vaccine than the women in the group who were not pregnant. In doctor-speak, a 'higher level of immune response' means a more severe infection.

This is an important finding because in the past doctors thought that pregnant women were simply more susceptible to getting the flu because their immune systems were weakened. But this study shows that in fact it is the strong response of a pregnant woman's immune system that causes her severe symptoms.

Given the fact that influenza is associated with quadruple the risk for premature delivery in pregnant women — and the fact that right now only 50 percent of pregnant women get vaccinated — health experts are emphasizing the importance of the flu vaccine as we head into influenza season.

Pregnant or not, talk to your doctor about the flu vaccine and when and where you can get vaccinated.